Depletion of CLK2 sensitizes glioma stem-like cells to PI3K/mTOR and FGFR inhibitors.

The Cdc2-like kinases (CLKs) regulate RNA splicing and have been shown to suppress cell growth. Knockdown of CLK2 was found to block glioma stem-like cell (GSC) growth in vivo through the AKT/FOXO3a/p27 pathway without activating mTOR and MAPK signaling, suggesting that these pathways mediate resistance to CLK2 inhibition. We identified CLK2 binding partners using immunoprecipitation assays and confirmed their interactions in vitro in GSCs. We then tested the cellular viability of several signaling inhibitors in parental and CLK2 knockdown GSCs. Our results demonstrate that CLK2 binds to 14-3-3τ isoform and prevents its ubiquitination in GSCs. Stable CLK2 knockdown increased PP2A activity and activated PI3K signaling. Treatment with a PI3K/mTOR inhibitor in CLK2 knockdown cells led to a modest reduction in cell viability compared to drug treatment alone at a lower dose. However, FGFR inhibitor in CLK2 knockdown cells led to a decrease in cell viability and increased apoptosis. Reduced expression of CLK2 in glioblastoma, in combination with FGFR inhibitors, led to synergistic apoptosis induction and cell cycle arrest compared to blockade or either kinase alone

The polo-like kinase 1 inhibitor volasertib synergistically increases radiation efficacy in glioma stem cells.

Background: Despite the availability of hundreds of cancer drugs, there is insufficient data on the efficacy of these drugs on the extremely heterogeneous tumor cell populations of glioblastoma (GBM). Results: The PKIS of 357 compounds was initially evaluated in 15 different GSC lines which then led to a more focused screening of the 21 most highly active compounds in 11 unique GSC lines using HTS screening for cell viability. We further validated the HTS result with the second-generation PLK1 inhibitor volasertib as a single agent and in combination with ionizing radiation (IR). Conclusions: Our results reinforce the potential therapeutic efficacy of volasertib in combination with radiation for the treatment of GBM. Methods: We used high-throughput screening (HTS) to identify drugs, out of 357 compounds in the published Protein Kinase Inhibitor Set, with the greatest efficacy against a panel of glioma stem cells (GSCs), which are representative of the classic cancer genome atlas (TCGA) molecular subtypes. Oncotarget 2018; 9(8):10497-10509

Dynamics of human replication factors in the elongation phase of DNA replication

In eukaryotic cells, DNA replication is carried out by coordinated actions of many proteins, including DNA polymerase δ (pol δ), replication factor C (RFC), proliferating cell nuclear antigen (PCNA) and replication protein A. Here we describe dynamic properties of these proteins in the elongation step on a single-stranded M13 template, providing evidence that pol δ has a distributive nature over the 7 kb of the M13 template, repeating a frequent dissociation–association cycle at growing 3′-hydroxyl ends. Some PCNA could remain at the primer terminus during this cycle, while the remainder slides out of the primer terminus or is unloaded once pol δ has dissociated. RFC remains around the primer terminus through the elongation phase, and could probably hold PCNA from which pol δ has detached, or reload PCNA from solution to restart DNA synthesis. Furthermore, we suggest that a subunit of pol δ, POLD3, plays a crucial role in the efficient recycling of PCNA during dissociation–association cycles of pol δ. Based on these observations, we propose a model for dynamic processes in elongation complexes

Feasibility Study on Soilless Cultivation of Organic Ginseng

Based on the present situation and problems concerning ginseng cultivation as well as soilless cultivation features, we analyze the growth indicators and input-output ratio of different ginseng cultivation patterns, and conform that the soilless cultivation technology for organic ginseng is feasible. And this technology provides theoretical basis and technological feasibility for the sustainable development of ginseng industry

AMPA receptors promote perivascular glioma invasion via β1 integrin–dependent adhesion to the extracellular matrix

High-grade gliomas release excitotoxic concentrations of glutamate, which has been shown to enhance tumor proliferation and migration. α-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) glutamate receptors are abundantly expressed at the invading edge of glioblastoma specimens, suggesting they may play an important biologic role in tumor invasion. In this study, we examined potential mechanisms by which AMPA receptor (AMPAR) expression and stimulation promote glioma cell migration and invasion. Overexpression of GluR1, the most abundant AMPAR subunit in gliomas, positively correlated with glioma cell adhesion to type I and type IV collagen, which was decreased in cells with knockdown of GluR1 and with blocking antibodies to β1 integrin. Furthermore, stimulation of the AMPAR led to detachment of cells from the extracellular matrix (ECM). Immunoprecipitation studies showed that GluR1 associated with the actin cytoskeleton-linked protein band 4.1B (brain type), which may serve as a link between GluR1 and integrins. Overexpression of GluR1 correlated with increased cell-surface expression of β1 integrin, increased phosphorylation of focal adhesion kinase (FAK-Y397), and enhanced numbers of focal adhesion (FA) complexes. Cells overexpressing GluR1 had increased colocalization of actin and paxillin at FAs and, in several glioma cell lines, significantly increased invasion in an in vitro Matrigel transwell assay. Likewise, in an intracranial xenograft model, overexpression of GluR1 led to perivascular and subependymal glioma cell invasion similar to patterns of tumor dissemination described in human glioblastoma. Together, these results suggest that AMPARs may link signals from the ECM to sites of FA, where signal integration promotes tumor invasion